rocfft: ppc64el FTBFS workaround (disable HIP client tests)

[Trupti <trupti@linux.ibm.com>]

Hello,

The build failures of rocfft on ppc64el are caused by a crash in 
clang/LLVM when compiling HIP code.
Specifically, compiling HIP client test sources triggers an internal 
compiler error in the LLVM PowerPC backend during code generation.
This is an upstream toolchain issue and not a functional problem in 
rocfft itself.

The compiler crash has been reported upstream and is tracked in the LLVM 
issue tracker: https://github.com/llvm/llvm-project/issues/168727

I tested a targeted workaround on ppc64el by disabling HIP client tests, 
while keeping the core rocfft library unchanged. With this change, 
rocfft builds and installs successfully on ppc64el.

Given this, would it be acceptable to apply a targeted workaround that 
disables HIP client tests on ppc64el, instead of removing the ppc64el 
binaries at this stage?


Thanks,
Trupti